Apparatus for and method of forming seals in an electrochemical cell assembly

Abstract

A sealing and repair technique is provided for forming complex and multiple seal configurations for fuel cells and other electrochemical cells. To provide a seal, for sealing chambers for oxidant, fuel and/or coolant, a groove network is provided extending through the various elements of the fuel cell assembly. A source of seal material is then connected to an external filling port and injected into the groove network, and the seal material is then cured to form the seal. There is thus formed a “seal in place”, that is robust and can accommodate variations in tolerances and dimensions, and that can be bonded, where possible, to individual elements of the fuel cell assembly. To repair part of an electrochemical cell stack, some elements are removed and either repaired or replaced. The cell assembly is then put together again and a bore is provided for injection of fresh seal material. This bore can either have been formed in the original assembly or is formed by mechanical removal of part of the original seal material

1 . An electrochemical cell assembly comprising: 
 (a) a plurality of separate elements, at least some of the elements including grooves for seals;    (b) a plurality of seals in the grooves between the plurality of separate elements, sealing the elements to control fluid flow;    wherein the elements and the seals are bonded together such that separation of two for more elements will result in damage to one or more of the seals and separate elements; and    wherein the electrochemical cell assembly includes, for each of at least some of the separate elements, a resealing portion permitting a bore to be formed therethrough to provide fluid communication to at least one of the grooves, whereby, in use, the electrochemical cell assembly can be at least partially disassembled, any damaged elements can be replaced, at least one bore can be formed through selected ones of said resealing portions connecting with said at least one of the grooves to form a groove network, whereby the electrochemical cell assembly can be reassembled and curable seal material can be injected into the groove network and cured to reseal the electrochemical cell assembly.    
   
   
       2 . An electrochemical cell assembly as claimed in  claim 1 , wherein said plurality of separate elements include a plurality of separate plates arranged generally parallel to one another, and wherein the resealing portions are such as to enable at least one bore to be formed extending substantially perpendicularly to the separate elements.  
   
   
       3 . An electrochemical cell assembly as claimed in  claim 1 , wherein the plurality of separate elements comprise a plurality of plates having edge surfaces and arranged substantially parallel to one another in a stack, the stack having side faces formed from the edge surfaces of the plurality of separate elements, and wherein the resealing portions enable bores to be formed extending from the side surfaces of the stack into the stack to communicate with at least one of said grooves.  
   
   
       4 . An electrochemical cell assembly as claimed in  claim 2  or  3  wherein each resealing portion includes an aperture in which said at least one bore can be formed.  
   
   
       5 . An electrochemical cell assembly as claimed in  claim 4 , wherein in an originally assembled condition of the electrochemical cell assembly, said at least one bore is empty.  
   
   
       6 . An electrochemical cell as claimed in  claim 4 , wherein, in an originally assembled condition of the electrochemical cell assembly, said at least one bore is filled with a sealant material.  
   
   
       7 . An electrochemical cell assembly as claimed in  claim 2  or  3 , wherein said resealing portions comprise solid portions of the separate elements, sufficiently spaced from any active areas and apertures of the separate elements, to permit a bore to be formed in use to provide access to said at least one groove.  
   
   
       8 . An electrochemical cell assembly as claimed in  claim 7 , wherein each of the separate elements comprises an active area, and a plurality of apertures adjacent to the active area and adapted to align with apertures of other elements to form manifolds for fluids extending through the stack , and wherein the resealing portions are provided between the apertures and the active areas and sufficiently spaced therefrom to permit said at least one bore to be formed in use.  
   
   
       9 . An electrochemical cell assembly as claimed in  claim 1 , wherein the resealing portions comprise apertures for a sealant aligned to form at least one groove manifold for the sealant extending through the plurality of separate elements, and wherein each said at least one bore comprises a bore extending within each groove manifold and spaced from sides thereof.  
   
   
       10 . An electrochemical cell assembly as claimed in  claim 9 , wherein each bore and each groove manifold are generally cylindrical.  
   
   
       11 . An electrochemical cell assembly as claimed in  claim 9 , wherein the plurality of separate elements includes a plurality of anode and cathode plates stacked parallel to one another, and wherein each groove manifold and each bore extend substantially perpendicular to the anode and cathode plates.  
   
   
       12 . An electrochemical cell assembly as claimed in  claim 1 , wherein the sealant material comprises a thermoset material.  
   
   
       13 . An electrochemical cell assembly as claimed in  claim 12 , wherein the thermoset material comprises a silicone-based material.  
   
   
       14 . An electrochemical cell assembly as claimed in  claim 1 , wherein the sealant material comprises a thermoplastic.  
   
   
       15 . An electrochemical cell assembly as claimed in  claim 9  which includes a transverse duct extending through at least one element of the electrochemical cell assembly to the groove manifold, for supply of the seal material during original assembly of the electrochemical cell assembly.  
   
   
       16 . An electrochemical cell assembly as claimed in claim in  claim 9 , wherein the groove manifold is open at both ends, to enable a rod to be inserted and located within the main manifold during assembly, to form each bore.  
   
   
       17 . An electrochemical cell assembly comprising:  
     a plurality of separate elements; 
 at least one groove network extending through the electrochemical cell assembly and at least partially between the plurality of separate elements, and including at least one filling port for the at least one groove network;  
 a seal within the at least one groove network, that seal having been formed in place from a cured liquid seal material after assembly of said separate elements, wherein the seal provides a barrier between at least two of said separate elements to define a chamber for a fluid for operation of the electrochemical cell assembly; and  
 for each of at least some of the plurality of separate elements of the electrochemical cell assembly, a resealing portion permitting at least one bore to be formed therethrough to provide fluid communication to at least one of the groove networks, whereby in use, the electrochemical cell assembly can be at least partially disassembled, and subsequently reassembled, with said at least one bore enabling a liquid seal material to be injected after reassembly for resealing the electrochemical cell assembly.  
 
   
   
       18 . An electrochemical cell assembly as claimed in  claim 17 , wherein the resealing portion comprise for each of at least some of the elements, an aperture aligned to form at least one groove manifold extending through the electrochemical cell assembly.  
   
   
       19 . An electrochemical cell assembly as claimed in  claim 18 , wherein the plurality of separate elements includes a plurality of anode and cathode plates stacked parallel to one another, and wherein the manifold extends substantially perpendicularly to the anode and cathode plates.  
   
   
       20 . An electrochemical cell assembly as claimed in  claim 19 , including a transverse duct extending through one element of the electrochemical cell assembly to at least one groove manifold, for supply of liquid seal material during original assembly of the electrochemical cell assembly.  
   
   
       21 . An electrochemical cell assembly as claimed in any one of claims  20 , wherein each at least one groove manifold is open at both ends, to enable a bore to be formed extending through the entire electrochemical cell assembly.  
   
   
       22 . An electrochemical cell assembly as claimed in  claim 17 , wherein said plurality of separate elements include a plurality of separate plates arranged generally parallel to one another, and wherein the resealing portions are such as to enable at least one bore to be formed extending substantially perpendicularly to the separate elements.  
   
   
       23 . An electrochemical cell assembly as claimed in  claim 17 , wherein the plurality of separate elements comprise a plurality of plates having edge surfaces and arranged substantially parallel to one another in a stack, the stack having ends and side faces formed from the edge surfaces of the plurality of separate elements, and wherein the resealing portions enable bores to be formed extending from the side surfaces of the stack into the stack to communicate with at least one of said grooves.  
   
   
       24 . A method of forming a seal in an electrochemical cell assembly comprising a plurality of separate elements, the method comprising: 
 (a) assembling the separate elements of the fuel cell together;    (b) providing at least one groove network extending through the separate elements and a filling port open to the exterior and in communication with the at least one groove network;    (c) connecting a source of liquid seal material to the filling port and injecting the seal material into the at least one groove network to fill the at least one groove network and simultaneously venting gas therefrom; and    (d) forming a bore in the seal material extending through at least some of the plurality of separate elements, and curing the seal material, to form a seal in the at least one groove network.    
   
   
       25 . A method as claimed in  claim 24 , wherein step (d) includes inserting a rod extending through apertures in said at least some of the plurality of separate elements, to form the bore.  
   
   
       26 . A method as claimed in  claim 25 , the method including providing said at least some of the plurality of separate elements with apertures, aligning the apertures to form a main groove manifold extending through the electrochemical cell assembly and providing the rod within the main groove manifold and spaced from sides thereof.  
   
   
       27 . A method as claimed in  claim 25  or  26 , the method comprising providing the rod within the electrochemical cell assembly prior to injection of the seal material into the groove network and removing the rod after the seal material has cured and set.  
   
   
       28 . A method as claimed in  claim 25  or  26 , the method comprising, after injecting the seal material to fill the groove network, inserting the rod to displace excess seal material, and subsequently curing the seal material.  
   
   
       29 . A method as claimed in any of  claim 24 ,  25  or  26 , including providing a thermoset material as the seal material and, in step (d), heating the electrochemical cell assembly and the seal material to cure the seal material.  
   
   
       30 . A method as claimed in  claim 24 ,  25  or  26 , including providing a thermoplastic as the seal material and, in step (d), cooling the electrochemical cell and the seal material to cure the seal material to cause the seal material to set.  
   
   
       31 . A method of forming a seal in an electrochemical cell assembly comprising a plurality of separate elements, the method comprising: 
 (a) assembling the separate elements of the fuel cell together;    (b) providing at least one main manifold extending through the plurality of separate elements and including at least one open end open to the exterior of the electrochemical cell assembly;    (c) providing at least one groove network extending through the separate elements and a filling port open to the exterior and in communication with the at least one main manifold and with the at least one groove network;    (d) connecting a source of liquid seal material to the filling port and injecting the seal material into the at least one groove network to fill the at least one groove network and simultaneously venting gas therefrom;    whereby, the provision of said at least one open end enables a bore to be formed subsequently through at least some elements of the electrochemical cell assembly, for reassembly thereof.    
   
   
       32 . A method as claimed in  claim 31 , the method including providing said at least some of the plurality of separate elements with generally circular apertures, aligning the apertures to form a main groove manifold extending through the electrochemical cell and forming said at least one open end.  
   
   
       33 . A method of disassembling and reassembling an electrochemical cell assembly comprising: 
 (a) a plurality of separate elements, at least some of the separate elements including grooves for seals;    (b) a plurality of seals in the grooves between the separate elements; the method comprising the steps of:    (1) separating the electrochemical cell assembly into at least two parts, each including at least one of said plurality of separate elements;    (2) cleaning and removing any existing seal material in one or more of the grooves on facing surfaces of said at least two parts of the electrochemical cell assembly;    (3) providing at least one bore extending through the electrochemical cell assembly, and communicating with each empty groove;    (4) reassembling the said at least two parts together; and    (5) injecting fresh seal material through the bore to fill each empty groove, and curing the fresh seal material to reform the seal between said at least two parts of the electrochemical cell assembly.    
   
   
       34 . A method as claimed in  claim 33 , the method including providing in the original electrochemical cell assembly, said bore as at least one bore extending through at least some of the elements of the electrochemical cell assembly.  
   
   
       35 . A method as claimed in  claim 34 , the method additionally including in step (4), providing a rod extending through the electrochemical cell assembly, prior to causing the seal material to set, to reform the bore in the electrochemical cell assembly.  
   
   
       36 . A method as claimed in  claim 33 , wherein step (3) comprises forming the bore by removing portions of the separate elements to form seal apertures, the seal apertures being aligned to form a groove manifold.  
   
   
       37 . A method as claimed in any one of claims  33  the method being applied to an electrochemical cell stack assembly including a plurality of alternating anode and cathode plates and a plurality of membrane electrode assemblies sandwiched between the anode and cathode plates, the method further comprising: 
 (a) separating the electrochemical cell assembly at least two locations including one of the plurality of membrane electrode assemblies;    (b) for the plates and membrane exchange assemblies between said two locations, effecting one of: separating individual plates, cleaning the individual plates of seal material for reuse, and providing replacement membrane exchange assemblies where required; and discarding all the anode plates, cathode plates and the membrane exchange assemblies located between said two locations and providing replacement, clean anode plates, cathode plates and membrane exchange assemblies;    (c) reassembling the electrochemical cell assembly; and    (d) injecting fresh seal material to fill the empty grooves and causing the seal material to set.    
   
   
       38 . A method as claimed in  claim 37 , the method comprising providing the original electrochemical cell assembly with at least one main groove manifold at least partially filled with seal material, the method further comprising removing the seal material from said at least one main manifold to form said at least one bore.  
   
   
       39 . A method as claimed in  claim 38 , including providing, at least within each main groove manifold, a thermoplastic seal material, and the method further comprising forming the bore by melting the thermoplastic seal material to permit removal thereof.  
   
   
       40 . A method as claimed in  claim 38 , further comprising mechanically removing the seal material from each main groove manifold, to form the bore.  
   
   
       41 . A method as claimed in  claim 37 , the method further comprising mechanically removing at least part of one of the elements to form the bore for supply of the seal material.  
   
   
       42 . An apparatus for providing a seal material to an electrochemical cell assembly for sealing various components of the electrochemical cell, the apparatus comprising: 
 (a) a main body;    (b) an inlet disposed near one end of the main body for receiving the seal material; and    (c) an outlet disposed near the other end of the main body for providing the seal material to at least one portion of the electrochemical cell;    wherein the main body generally has an appropriate shape for leaving a bore in the electrochemical cell after the seal material has been delivered to the electrochemical cell.    
   
   
       43 . The apparatus of  claim 42 , wherein the main body includes an inner member and an outer member, the inner member including a slot for providing the seal material to the outer member and the outer member having a plurality of apertures vertically displaced from one another for providing the seal material to various portions of the electrochemical cell assembly.  
   
   
       44 . The apparatus of  claim 43 , wherein the slot on the inner member is substantially vertical and the apertures on the outer member are horizontally displaced from one another and the apparatus further includes a rotation means for rotating the members with respect to one another so that the apertures provide the seal material to the various portions of the electrochemical cell assembly in a sequential manner.  
   
   
       45 . The apparatus of  claim 43 , wherein the slot on the inner member is displaced at an angle, the apertures on the outer member are substantially vertical and the apparatus further includes a rotation means for rotating the members with respect to one another so that the apertures provide the seal material to the various portions of the electrochemical cell assembly in a sequential manner.  
   
   
       46 . The apparatus of  claim 43 , wherein the apparatus further includes a rotation means for rotating the members with respect to one another and the slot on the inner member and the apertures on the outer member, when aligned, are disposed such that at most only one of the apertures is aligned with the slot when the members are rotating so that seal material flows through the apertures one at a time.